ARTIFICIAL SELECTION 



97 



Leaving Burbank's other fruit and berry creations un- 

 noticed, we may refer to his curious cross-bred walnut results 

 (Fig. 63), the most astonishing of which is a hybrid between 



FIG. 63. At left, leaf of English walnut, Juglans regia; at right California black 

 walnut, Juglans californica; and in the middle a leaf of the hybrid Paradox, first 

 generation. (From photograph by Burbank.) 



Juglans Californica (staminate parent) and J. niyra (pistillate 

 parent), which grows with an amazing vigor and rapidity, the 

 trees increasing in size at least twice as fast as the combined 

 growth of both parents, and the clean-cut, glossy, bright green 



